L18 - Digestive system

• What are the four main functions of the digestive system?

  Take in food, break it down, absorb nutrients, rid indigestible remains
• What is the gastrointestinal (GI) tract?

  A continuous muscular tube for digestion and absorption
• What are the accessory digestive organs?

  Teeth, tongue, salivary glands, gallbladder, liver, pancreas
• What are the six activities of processing food?

  1. Ingestion
  2. Secretion of digestive enzymes
  3. Motility
  4. Digestion
  5. Absorption
  6. Defecation
• What is peristalsis?

  Propulsion of food via alternating contractions
• What is the role of mechanical breakdown in digestion?

  Physical breaking and mixing of food with enzymes
• What is the function of the peritoneum?

  Covers digestive organs and lines the abdominal cavity
• What is the difference between visceral and parietal peritoneum?

  Visceral covers organs; parietal lines cavity walls
• What is mesentery?

  Double layer of peritoneum connecting organs to the body wall
• What are the two folds of visceral peritoneum connected to the stomach?

  Greater omentum and lesser omentum
• What are the four layers of the digestive tract and their functions?

  1. Mucosa: Secretion, absorption, protection
  2. Submucosa: Contains blood vessels and nerves
  3. Muscularis externa: Peristalsis and segmentation
  4. Serosa/Adventitia: Attaches GI tract to structures
• What is the enteric nervous system (ENS)?

  In-house nerve supply for the GI tract
• What do chemoreceptors in the ENS sense?

  Osmolarity, pH, substrates, and digestion end products
• What does the myenteric plexus control?

  Strength and rate of contraction in the GI tract
• How does the autonomic nervous system regulate digestive activity?

  • Parasympathetic: Increases ENS activity, motility, and secretion
  • Sympathetic: Decreases ENS activity, motility, and secretion
• What is the role of enteroendocrine cells?

  Produce hormones controlling secretion or contraction
• What is the function of the greater omentum?

  Hangs from the stomach and covers intestines
• How does the parasympathetic system affect GI tract motility?

  It increases motility and digestive canal secretion
• How does the sympathetic system affect GI tract motility?

  It decreases motility and digestive canal secretion
• True or False: Peristalsis is the mechanical breakdown of food.

  False
• True or False: All parts of the digestive canal have a serosa.

  False
• True or False: The greater omentum hangs over the front of the intestines.

  True
• True or False: The myenteric plexus controls strength and rate of contraction of the GI tract.

  True
• True or False: The parasympathetic system decreases GI tract motility.

  False